“It was fun. It was a lot of fun,” Messina told Stephen Colbert on Wednesday night of his task to pack on the pounds. “Just stuff my face, beer, lots of beer, bagels, pasta. I would have a beer by the bedside table and when I woke up in the middle of the night to pee, I’d just [chug] the beer. It was fun… I was like a hero on set because Affleck and the rest of the crew would be like, ‘How much do you weigh?’ They’d feel my belly.”

Messina wanted to fill out to match his character in the book version of Live By Night.

“In the book the character is described as round, and I’m Affleck’s side kick and kind of, believe it or not, body guard so I figured the only way to maybe do that was to get fat,” he explained.

The upcoming gangster film, set in the 1920s Prohibition era, is based off the 2012 novel by the same name and also stars Zoe Saldana and Elle Fanning.

"It's kind of a classic, throwback gangster movie," Affleck recently told ET. "It kind of harkens back to the classic era of cinema, I hope. It's meant to be a love letter to the great movies of old, where you had great sweep and scope and extras and design and big, sexy, punchy themes."

Live By Night hits theaters on Jan. 13. For more on the film, watch the clip below!